%\usepackage{tikz}
%\usetikzlibrary{trees}

\pagestyle{empty}
\begin{figure}

% Set the overall layout of the tree
\tikzstyle{level 1}=[level distance=3.5cm, sibling distance=3.5cm]
\tikzstyle{level 2}=[level distance=3.5cm, sibling distance=2cm]

% Define styles for bags and leafs
\tikzstyle{bag} = [text width=4em, text centered]
\tikzstyle{end} = [circle,minimum width=3pt,fill, inner sep=0pt]

% The sloped option gives rotated edge labels. Personally
% I find sloped labels a bit difficult to read. Remove the sloped options
% to get horizontal labels. 
\begin{tikzpicture}[grow=right]
\node[bag] {$\Omega$}
    child {
        node[bag] {$(P,\cdot)$ \\ $\frac{1}{3}$}        
            child {
                node[end, label=right:
                    {$(P,V) \rightarrow P(\{(P,V)\})=\frac{1}{3}\times\frac{1}{1}=\frac{1}{3}$}] {}
                edge from parent
                node[above] {$V$}
                node[below]  {$\frac{1}{1}$}
            }
%             child {
%                 node[end, label=right:
%                     {$(C,K) \; P(W_1\cap B_2)=\frac{4}{7}\cdot\frac{5}{9}$}] {}
%                 edge from parent
%                 node[above] {$B$}
%                 node[below]  {$\frac{5}{9}$}
%             }
            edge from parent 
            node[above] {$P$}
            node[below]  {$\frac{1}{3}$}
    }
    child {
        node[bag] {$(V,\cdot)$ \\ $\frac{2}{3}$}        
        child {
                node[end, label=right:
                    {$(V,V) \rightarrow  P(\{(V,V)\})=\frac{2}{3}\times\frac{1}{2}=\frac{1}{3}$}] {}
                edge from parent
                node[above] {$V$}
                node[below]  {$\frac{1}{2}$}
            }
            child {
                node[end, label=right:
                    {$(V,P) \rightarrow  P(\{(V,P)\})=\frac{2}{3}\times\frac{1}{2}=\frac{1}{3}$}] {}
                edge from parent
                node[above] {$P$}
                node[below]  {$\frac{1}{2}$}
            }
        edge from parent         
            node[above] {$V$}
            node[below]  {$\frac{2}{3}$}
    };
\end{tikzpicture}
\label{diag:tree_urna_s}
\caption{Arvore que descreve o experimento composto de duas retiradas de bolas uma urna contendo 2 bolas vermelhas e uma preta sem reposi\c{c}\~{a}o.}
\end{figure}